Electrical connectors that are connected to printed circuit boards include the type which have terminating sections of electrical contacts that are inserted into holes in the printed circuit board and are soldered to conductive areas of the circuit board. The surface mount type of electrical connector has electrical contacts whereby the terminating sections are surface soldered to conductive areas on the printed circuit board thereof. Recently, because of higher complexity and greater compactness of circuits on the printed circuit board, connector contact spacing has become smaller (for example, 1 mm); correspondingly, it has become difficult to drill holes close enough in the printed circuit board, thus the need for surface mount connectors has been increasing.
In surface mount connectors, aside from electrical connection to the printed circuit board, there is also a need to mechanically secure the connector thereto. This was previously done either by providing a projection on the bottom of the connector and inserting it into a hole in the printed circuit board to secure it thereon, or by a metal plate on the bottom of the connector and soldering it to the printed circuit board.
In the former case, it is necessary to machine holes in the printed circuit board for insertion of the projections; it is also necessary to provide the projections on the connectors, thereby creating disadvantages from the standpoint of connector-manufacturing costs or securing the connectors to circuit boards. In the latter case, extra surface area is taken up by the metal plate on the printed circuit board, especially where demands are strong for higher density and greater compactness, thereby creating the problem that effective surface area on the printed circuit board is reduced.